Nois abatment for business jets [Archive]

tommoutrie

2nd Apr 2009, 00:24

I comply with the spirit of icao 8168 - I make all endeavours to minimise the noise footprint on take-off. I do that on landing too if at all possible. I do not use the prescribed noise abatement techniques because I have dismissed them on safety grounds. I've tried it once in the CJ2+ and it requires a nose up attitude of 40 degrees to keep V2+10 and the aircraft was climbing at 5000fpm. An engine failure with this body angle and lack of speed is difficult to handle and I think the whole procedure is pointless given how quiet the CJ is. At many airfields this departure is dangerous - at Farnborough for instance where we depart under very busy London airspace we would be likely to trigger TCAS RA's in aircraft above us. Also, we often depart into uncontrolled airspace and flying the NADP enormously increases pilot workload and reduces capacity for lookout. A secondary consideration after safety is my passengers comfort. I don't believe that they pay for a fairground ride and I don't want to clear up the puke.

In short, I've junked it on the grounds that it is dangerous for the type I most often fly and if anyone from the CAA would like to pay for a circuit I will demonstrate why. They won't like the initial climb and when I fail an engine at 600 feet with the nose pointing straight up I think will actually be able to get them to let out a little poo...

I keep finding badly thought out "global" rules and would like to know how to contribute to some of the decision making processes in aviation that make my life difficult. Not being able to fly two types until you've logged 500 hours and 2 OPC's under one AOC prevents experienced pilots helping out on less experienced fleets. The blanket JAR-OPS factoring for landing performance regularly forces pilots to carry less fuel than may actually be safe (but whoopy doo, its legal). have got loads of them....

hands up, who else completely ignores the NADP 1 and 2

Grum

2nd Apr 2009, 07:47

I ignore them for similar reasons.

In Falcon 2000 I can't rotate fast enough to keep V2+10, I will have accelerted through it only to have to keep pitching up to get it back.

Then many deprtures under busy airspace only take you to 2000feet. So by the time i hit 'One to go' I need to get that VS below 1000fpm to avoid triggering the TCAS. The plane is pretty quiet so climb assertively but comfortably.

What is the priority? Last 1000ft at rapid climb for noise abatement or shallow climb for TCAS reasons?

SimJock

2nd Apr 2009, 08:12

It does seem wrong to talk about limiting speed and aoa in terms of reducing noise footprint. Surely a de-rated thrust take off is of more value in reducing engine noise. If you have to firewall the throttles in order to maintain your V2+10/20 then clearly you have an old/heavily loaded/underpowered jet that could do with new engines or hushkits :hmm:

SimJock

2nd Apr 2009, 08:41

Thats nice bral :ok: is that chapter 3, chapter 4 or are we into an appendix ?

I wish they were all like that. I was looking at this subject recently and I'm not sure when this all started, but it seems that under EASA, aircraft have to be certified with and carry a noise certificate. I recall that the Germans were always very keen on this for all aircraft and now it seems we all (Europe) have to comply. I wonder how much longer the remaining european Chapter 2's have before hushkitting or an operating ban is forthcoming from our Euro masters.

PPRuNeUser0215

2nd Apr 2009, 09:44

NADP 2 and Doc 8168 (the base document) say it is between V2+10 to V2+20.
Most if not all operators under an AOC (that means with some kind of approved books on how the company wants you to operate their aircrafts) have a published Max body angle. Quite commonly found to be 20 degres (so far from light jets to heavies I have flown, I have found it to be 20 degres - PLI on the Boeing or just attitude indicator on others).

Therefore nobody is expected to pitch up at 37 degres in a commercial environment but everybody can fly NADP2 without finding himself in such attitude. So one should make all efforts to follow NADPs as they form full part of the EU OPS 1 which is law. But keep in mind that max body angle published somewhere as it is an aircraft limiting factor (kind of a Soft limitation, as opposed to a Hard one - such as a manufacturer, structural one).

As for noise and derated take off, this is an engine life preserving tool, not an anti noise procedure. Please I am not saying that in order to achieve approval at sensible airports, manufacturers will not bring in an early thrust reduction during climb. Not the same.
Also if many of you know about derated takeoff but many don't so if you don't may I suggest you don't do it just as you feel. There is a max amount of derate you can do, depending on a couple of factors. It is simply not just a case of not applying full thrust at take off...:cool:
Plus what creates most of the noise is not the engines (yes I know engines make noise) but the drag. During an approach (slight drift) an aircraft with all flaps and gear will generate a lot more noise that one who keeps to minimum clean as late a good airmanship dictates (check the criteria for a stablised approach).
Of course as you clean up (back to the departure part), less power is required so less noise is generated.
So if you want to be a good neighbour and a good operator, you derate (as per the company approved books) to save on the engine, you climb at V2+10-V2+20 up to 800' (or Max body angle), clean up+reduced to climb power or whatever is appropriate for that first stop altitude in your SID/clearance.

Nothing fancier than that as far as I am concerned. Works for a powerful light jet (aren't they all, these little rockets) as well as an empty 767-300 with no more than a few tonnes of fuel for a 20 mins ferry (just as amazing as bizjet).
But ! Beware of your aircraft performance, automatics limitations. A good brief helps keeping the fast pace.

Cheers all.

jr of dallas

2nd Apr 2009, 11:11

Man, you know it all !:ok::ok::ok: thanks I really feel safer now..

CL300

2nd Apr 2009, 11:20

I can speak only for the falcons,

the falcons meet stage 3 or 4 limits ONLY when reducing N1 ( around 10 to 14 percent). A noise abatment is not a race to altitude, it is a way to reduce the noise, would it be close or distant. In any case it calls for a thrust reduction.
If you take the 7X out of LCY, the N1 reduction is quite impressive and it is done at 400ft....

ICAO is asking for a thrust reduction at 800ft, shouldn't it ring a bell ?
Nethertheless, our engines are making noise on take Off, and to reduce it, you need to reduce thrust. REad carefully, Jepp Book1 ATC pages 251 and on.

Jar Ops is even clearer asking for every operator to have noise abatment procedure and to use it every time for every airport.

The tendancy through airports is to design specifics procedures for their departures. The only advice is to read the pages 10-4.....

inner

2nd Apr 2009, 12:35

We ignore them as well. We don't like to climb with 6000'/min in Uk airspace (don't want to trigger tcas). Only when there is absolute no traffic and somewhere in the middle ofnowhere without pax, yes we do that.

tommoutrie

2nd Apr 2009, 13:54

I've got no maximum body angle in my part B and there is no procedure to de-rate take off power in the CJ (the FADEC requires the use of take of thrust because the software may go into the incorrect schedule otherwise). I don't fly the noise abatement procedure because its inappropriate and unsafe in the CJ.

Does anyone do it?

PPRuNeUser0215

2nd Apr 2009, 14:29

. I don't fly the noise abatement procedure because its inappropriate and unsafe in the CJ.
Not having a go Tommoutrie (that's my disclaimer to avoid the usual pprune slagging off match) but I fly the citation too and do follow the NADP2. I have not seen any problem other than the things I mentioned above such as low level alt cap (say less than 3000' for cash). Just something to be aware of and either you hand fly it or TCS it with the appropriate thrust reduction during the climb. I have not seen where it is unsafe either. From my experience in order to get rates in the 6000 fpm, it takes a bit of time for the aircraft to gather the energy required and usually it will not be a problem as it is more time than it takes to reach the 800' AGL from lift off. I can't reallt speak for the Lears as I have never flown them and I understand these things are quite something but I doubt that in general NADP is unachievable for Bizjets in a safe manner. Happy to hear more though.

Inner, just to clarify, it is only the NADP and it stops at 3000' so what you do after that is just basic airmanship. 6000 fpm might be or might not be appropriate depending on the place and time but that's not part of the departure (read disclaimer above ;) ). As an aside if you fly fast jets (privately, lucky you :cool:) with no flaps, the minimium noise acceleration altitude is 400' so super performing jets are also covered and the neighbours are "legally" happy.

CL300, you mean EU OPS ;)
About the 400' I believe it is a figure which is used as a minimum for aircraft certification (but I can't remember if it is for the single engine acceleration altitude or for noise although I suspect it is the 1st one) so I guess this where Mr Dassault comes from. It is the minium safe covering all cases including the noise restrictions in place. I stand to be corrected of course and I apologise for the inacuracy.

Still, when noise abatment (reducing) procedures are in place, either through the manufacturer, EU OPS or local authorities, we should all aim to follow them. If it is not possible then I guess we should inform the relevant people so it can be amended. At no time though I am suggesting that good airmanship should be binned but in most cases, all this is perfectly compatible.
Never following NADP if you are an OAC holder is not an option (as explained by CL300) but there is always room for special cases (which might be always for you if you are based at a place with that kind of step climb restriction).

airmen

3rd Apr 2009, 10:00

Well thank you all, sorry to take time now, I have been busy...

It seem that controversy is in the air!

I see a lot of existing regulations never followed by a hand full of professional pilots, and it always surprise me, why?
Because, when the rules where defined it brings a change in our habits and I think pilots should be flexible individuals and adapt to new things rather quickly.
It is always a lot of discussion on the subject and findings ways to explain that it is not possible to do it and etc. etc. however, if you react like this, you create your own rules and this is no way to serve aviation as professionals.

This particuliar set of NADP is not something optional and I personally comply with, not doing a ROC of 6000fpm as some said, you climb with max body angle 15-20° pitch and at 800 AGL set Climb power an clean up at 3000AGL, not so difficult...

Cheers

CL300

3rd Apr 2009, 10:08

AMEX :cool:

Some people and companies still do the 1500ft cut back ( when they do it).. so JAr-OPS vs EU-OPS should not bother them too much.. :O But I should have been more accurate, shame on me !!!

Empty Cruise

3rd Apr 2009, 10:48

Fly one of the best-climbing BJs out there - and if you pitch to 17 deg. ANU after TO and use LVL CHG mode, there are no speed excursions (V2+20-25), no excessiove ROC (3000 fpm) and no complaints from the back.

1500 ft AAL (or whatever AA is), we wind the speed up, run the flaps in, set CLB and - hallelujah, we've flown NADP A without any fuss. And much less workload than when people want to retract the flaps at 400 ft and have to pull the thrust back because speed is getting away from them.

If we could stop focussing on V2+10 EXACTLY, then it suddenly becomes managable. Next time - with the usual disclaimers about auhorisation from CP/TM/FM etc etc - try rotating at your target rate till you reach an attitude where the speed stabilises. Note this attitude, and the speed attained - if you are more than V2+30 I'd be very surprised (or your AFM dictates a very slow rotation rate, less than 2 deg/sec).

Stating that certain BJs cannot safely fly an NADP might not exactly be true. Stating that certain pilots or companies have procedures that do not sit easily with flying an NADP is probably 100% true - and stating that certain individuals feel so strongly about the way they have always done things that they would resist a change, probably lies in between the aforementioned on the truth-index :rolleyes:

Oh well, vive la difference :}

Empty

haughtney1

3rd Apr 2009, 11:13

Empty Cruise, with respect mate.....you need to qualify your comments in respect of thrust settings, basic T/O config and types of airspace you operate into.
I'm currently flying the Falcon 900 Easy, as such there are no numbers to derate for takeoff..so its full thrust each and every time...which means unless we are operating above about 90% MTOM even V2 + 40 will give about 25 degrees nose up
Dassault in their typically arrogant way have designed an unbelievably complicated procedure for noise abatement that is just manageable for places like Charles De Gaulle or Heathrow...but complete crap for London City, Farnborough, or anywhere else where there is a low level departure.
We have have our own procedure...it works very well, and involves a thrust reduction at 400' AAL :ok:

Empty Cruise

3rd Apr 2009, 12:05

Haughtney,

Like you, we have no way to de-rate (except doing an engine bleeds on T/O). I am familiar with Dassault not being the easiest for procedure design :ugh:, and appreciate that 1500 ft. might still be too high for thrust reduction on some aircraft.

Was unaware that the 900 had so much ooomph, but hey, live and learn. 25 deg. ANU is clearly not what you're looking for ;). However, there is some way from saying that yes, some aircraft are very high-powered, to saying that NADPs should just be disregarded (as some other posters suggested).

Main thing is, you have a way of dealing with it and roll back the thrust a bit earlier, we do 400 ft. as well out of TEB due to the 1500-ft. level-off. It was just the 37-deg. V2+10 -story that got my goat a bit. A happy modicum, where the punters are happy, the pilots comfortable and not overloaded and noise still implemented as an SOP - that'll have to do :ok:

Stan Woolley

3rd Apr 2009, 17:57

It's seems to me that the problem here is largely down to the fact that very few bizjet's fly derated takeoffs.

I'm not surprised they are challenging at full power all the time. Crazy!

Does anyone derate as a matter of course? Which types?

TWOTBAGS

3rd Apr 2009, 18:27

From personal experience

NO Derate, Hawker, Falcon 900

De rate available: BBJ we had 26K engines and always used 24k or 22k options.

In the Hawker we regularly used a standard departure with climb pwr @ 400ft because we simply would out climb or exceed the speed limit if we did not. TEB is the classic.

LEVC

3rd Apr 2009, 20:29

I've read with attention all posts, and i do not think that NAPD I or II can be done in all types of Bizzjets without trouble.

In my short experience with bizzjets (so far i have only flown one, the Lear 60),i am inclined to say that you can't fly V2+20 or whatever you want to stablish as a speed whitout having problems with too high nose attitude, excessive ROC, etc etc, this aircraft is a rocket, there is no derated procedure and the thing will climb at way over 8000 fpm while doing 250 kts at low levels, if not taken care of, altitude busts are an issue with this ROC (A/P isn't fast enough and a good reduction of thrust in advance will help avoiding the bust), imagine how it will go if you try to maintain V2+20 :eek:.

I would say that trying to perform NAPD's with this type is unnnecessary, the aircraft will be way over 5000' AGL only 1 minute after lift off, it just does not make sense to try to do it:=.

LEVC

PPRuNeUser0215

3rd Apr 2009, 22:54

Empty Cruise, airmen... Quite agree with you. Some aircraft aside, crew resiliance is a factor.
I have not done the calculation but regardless of the fact the aircraft performance, stating high climb rates to justify the non compliance, is in most cases, not good enough.
Indeed 6000 fpm, 8000 fpm are achievable climb rates in all aircrafts (decent ones and not just bizjets) but as mentioned, with the correct rotation rate (2 to 3 degres per sec up to initial climb pitch angle - prob 15 to 20 degres as per the manufacturer's books-), to reach 8000 fpm by 800' (EU OPS), you will probably need to pull some Gs or feel the horizontal acceleration most civilan jets are not commonly expected to do during what is essentially..... A most ordinary take off.
Sure if people talk about an ALT Cap (Step climb) by 1 or 2000's, it is a different ball game and basic airmanship and aircraft control should be maintained.
If in some cases, which I m sure, represents a minority, NADP really doesn't work then so be it... But dismissing it on the basis that because we fly Bizjets is not the best solution either. We ought to really study it and try it until all efforts are confirmed fruitless.
Remember, the environmentalist will get us if we don't do our best. They will because there are in greater number than us which makes it in the interest of our very own self preservation to keep these people the happiest possible. Who knows ? If we do a good job we might even be able to prove that we are not as bad as people think and that a few more slots here or there should not be denied to us. My way of thinking anyway.

For those mentioning high body angles (37) and no maximum published in the part B, there is another restriction.... Which is the one defining unusual attitudes. So perhaps as a personal limit if nothing is published then such limit could be used. Sorry no number in mind without checking but it is just like banking to 60 degres.... Aircraft can do it but not a normal way of flying.

CL300 I guess it is all that noise where you live which made you tired ;)

Final point... 1500' is the old procedure as explained (yet shown in your jepps, Text, page 251 etc). Not valid anymore although some airport will still would like you to follow it (think Bologna is one of them as an example clearly stated in the Jepps notes).

Good night all and thanks for keeping the debate so civilised. ;)

CL300

4th Apr 2009, 09:54

NADP can be flown in ANY aircraft, having around 14 bizjet type ratings from the wonderful slowtation to the GLEX through LR 20 and 30 series and the whole falcon family, and after circa 10K hours, It is easily doable even with an early level off ie KTEB or LFMD.

What is lacking is training. How often do you train at your various training providers to NADP ? I know the answer.
And then, since we are highly trained to fly at V2 at n-1, we have big trouble doing it on all operating.

The fundamentals are very easy, you have to reduce your noise footprint, on take off, for close-in engime matters, for distance, configuration is as important.

As an example, Cannes Airport LFMD, is actively into 'green effect', with noise, flight track monitoring, wed designed mandatory briefing, and hefty fines for non compliant flights up to ban specific planes/operators/pilots.

Just to say, you may not like it, nor think this is doable or achievable, but the noise foot prints are modelized , and if you mak too much noise, you will have to pay, and when you will be banned, you will lose your job...

Ready for thrust reduction ? and clean configuration on downwind ?

I bet you will be, after all, when going to KSMO or EGLC you are doing it , so...

Off to the beach...

Dumbledor

9th Apr 2009, 15:24

Our SOP for the LJ45 is 15deg pitch & T/O pwr to 1000'AAL (or later if necessary) then max continuous for climb pwr or less. No complaints from LCY yet. :ok:

Had noise complaints when flying the Citation V (with JT 15D-5 engines) out of LCY in around '98, so we had to reduce pwr early after T/O. These engines are on the Beechjet 400, which make the ramp at LCY extremely noisy at times (Sorry I can't call it a Hawker 400. I have flown a HS125-400 - is that not a called a Hawker-400 now? :ugh:). I believe the fans on these are not geared down unlike the Garrett (now Honeywell) engines in Lears and Hawkers. They spin at the same speed as the rest of the LP spool. That's why they windmill so well! :}

D

Dumbledor

9th Apr 2009, 16:10

I agree with CL300 about the clean config downwind within reason. It depends on what speed you're given (Cannes). At least no more than take off flap is req'd. It's quite easy to use the Gear and/or App flap as an airbrake to slow from your downwind speed to the target speed for base leg, start the descent with a semi circular turn onto final without level off. The power can normally remain constant from DW until the final spool up for full flap on final. This works on at least 3 types of Bizjet. This is the best way to cut down on noise in the circuit. Power against Gear or Appr flap in level flight is bad energy management.

Paradise Lost

9th Apr 2009, 19:29

As the agent provocateur in the 37* NU saga, which appears to have ruffled some goats/ feathers, I now own up to using "flex" or derated power on most of our take-offs; first because it's easy on my type to select on the FMS, and secondly because I'd like the engines to remember I was kind to them, and third because it makes almost silent BR700's even more neighbourhood friendly!
As plenty of subsequent posters commented, many a/c when empty and over powered are capable of extreme deck angles and rates of climb, so the AFM published procedures need to be treated with some caution, such as a limiting deck-angle if one is not published elsewhere in the manual.

Dumbledor

10th Apr 2009, 23:20

PL, I'm all for cutting down noise when we can but I don't like the idea of graduated take off power unless it was forced on me by the company. (We can only set T/O pwr on our machines like most bizjets anyway.)

What would bother me is that that V1 would come up closer to the end of the RW, giving less margin for stopping before V1. Also with an engine failure after T/O you would be lower or slower or both (ie less energy) than if you had full T/O pwr up till then.

Most modern bizjets (JT15D-5 powered less so) are pretty quiet nowadays, rotate early compared with the airliners, climb better and therefore are high enough not to trigger the noise monitors.

I can't see what is wrong with the pitching to 15deg (our SOP) or 20deg or whatever is comfortable with T/O pwr and reduce at say 1000' or 1500'AAL to climb pwr after that. Then at least you have put the maximum energy into the a/c untill then. Also you have cleared the bird strike risk level quickly and cleared the noise monitors with a good margin.

PPRuNeUser0215

11th Apr 2009, 10:23

Unless you are derating according to the approved procedure, you are invalidating all T/O performances worked out. It is a dangerous thing to do if it is done without backed up data, charts or officially approved criteria.
Also the idea of preserving the engine (unless following the above mentioned procedure) is what people flying Sencecas think and for a good reason. Piston engines are nowhere near as reliable as jet engines and a lot more prone to mishandling (cooling, oil level etc...). Jet engines are revolutionary in many ways and in no way comparable to pistons. They are built to be used at T/O power for 10 mins minimum (check the manufacturer's book) and they are usually (if not always) derated by the manufacturer so you get the maximum lenght (hours) before you have to bin it.

I am with Dumbledor and CL300 and the myth noise abatment departure cannot be flown with a biz jet is just that. A myth. On the other hand it is easy to see that people who cannot/do not want to follow a simple procedure, will come up with all sorts of homemade solutions. Not very good.

My philosophy is the following. You should always try to do the right thing because even when we try, we can fcuk it up. If you, deliberately deviate from the right way of doing things then you are getting yourself closer to the edge... Added to that the "fcuk up" factor and the road to recovery is going to be a tricky one for you (but that s ok because you decided to put yourself there) and for your colleague and PAX, which is not ok because they probably were not given the choice.

Paradise Lost

11th Apr 2009, 14:58

DD and AMEX, there was a clue in my previous post (BR710's) as to which type I am operating.....actually could be a G550 or a GLEX, but in both cases the Flex take-off option gives you all the revised performance data automatically, and by the way, restores full power on the good engine automatically in the event of an engine failure or on both in the event of windshear.
I would therefore suggest that it is not "a dangerous thing to do", but the correct way to operate those types where the derated power is an option for the reasons in my earlier post. If the type you operate does not support a derated power setting, then obviously don't derate!

PPRuNeUser0215

11th Apr 2009, 17:06

Replying after your post doesn't necessarily means the finger is pointed at you Paradise Lost :)
As for the engine type you fly, I am not familiar with it (I am P&W, RB211, CFM kind of guy... so far) but if you say, there is an approved method for derating at T/O then (and assuming you still want play Cluedo), here is another clue in what I said too
"Unless you are derating according to the approved procedure, ". My very first words in fact in that post below yours.

So now we agree that nobdoy should come up with their very own derating method simply because they have trouble flying a noise abatement departure procedure. Bearing in mind that in the GA World, operating standards remain unchecked for many (yeah ok, the odd OPC/LPC if under an AOC), bad habits due to a lack of knowledge or understanding tend to develop easily. That was my point I guess, hence my comment about "dangerous thing to do".

Peace ? :D

Paradise Lost

11th Apr 2009, 18:52

And love AMEX!

G-SPOTs Lost

11th Apr 2009, 21:35

Its all very well quoting rules and regs and following them to the letter, in reality none of us are bothered about how much noise we make on departure we are bothered about getting caught and fined.

Now before I get leapt on Im not on about Cannes or London City, invariably we are not coming out of these places very heavy.

Consider the monitoring points, also consider that the vast majority of airports who apply monitoring have huge runways and what do we realistically use 1/3 maybe 1/2 so we have maybe 1-1.5 kms head start on heavies, so going for it on t/o (unless im empty and in the mood) is a no go for me, Im a handful off power as soon as I get the clean wing call kind of man never had any problems yet.

I recall in the Excel 65% would give me 230knts and 2000fpm, you're not going to get found out in an excel at 65% N1 or any other bizjet I can think off.

Focusing on this V2 + X on a busy departure with no autothrottle is not a good demonstration of airmanship better to dump all the noise on the runway and be passing the upwind numbers with a clean wing and a sensible N1 and reduced climb rate after all its the N1 thats making all the noise not the physical position of the aircraft!

Off course terrain/conditions considered before I get pounced on by the H&S police

Empty Cruise

11th Apr 2009, 23:51

OK, we have now moved from "not bovvered" with noise abatement (something I at least can understand the rationale behind, although I just happen to find not bovvered = lazy) to experimental derates to keep our beloved 10 degree deck angle and still keep the noise police happy.

Now, this is where my understanding starts going a bit out the window... apart from the proper kit (derate via FMS or TMC), where exactly do you set this derated N1? On the runway??? After gear up??? When you have enough altitude that you're happy with having someone play with the TLs?

Please enlighten me as to who has validated these numbers, the performance involved, the SOPs, the ETPs... :ugh:

Common sense - just as full whack and 37 deg. ANU to keep +10 sure ain't the answer, just as surely the exerimental derate route ain't the answer either. None of these aircraft are the space shuttle, ladies and gents - they are simple pieces of equipment to fly, and they generally agree with simple procedures. In Empty's little book, if any actions apart from G/U are required below 1500 ft. AAL, then summat ain't right :E

KISS - works every time

CL300

12th Apr 2009, 09:12

ICAO doc 8168 ( ATC pages of your beloved Jepp Book 1 pages 251 and beyond for a summary) plus the AFM for the respective aircraft is giving the indication on how to fly a NADP.

Let's take the falcons, and due to my age, just the last type flown for me ( F2ESy) This aircraft meets stage 3 requirements at take off, with a thrust cut back of 12 per cent (afm) and stage 4 with a cut back of 13 per cent.

This aircraft flight director does not know the pitch he knows only the path (relative to the ground, therefore airborne). AFM recommends a path of 12 deg after airborne to meet noise abatment profile ( along with the thrust reduction) limited to 20deg pitch. The wing though cannot care less about your path, this is a by-product, the wing cares about speed AND AoA , that you command with your pitch, The Falcon 2000 EASy, has a pitch attitude on take off at 11 deg, attitude to be inceased to around 20 deg, in order to get the 12 deg of path... where is your speed at that point ? somewhere between v2+10 and Vft, What is your Rate of climb ? Around 2500 ft/mn. Do you need autothrottles ? no... You just fly...Speed decay? pitch down.. Speed increase ? pitch up to 20 max or reduce furthermore.

Engine failure ? firewall everything, and keep your speed !

Dassault had develloped for the F7X at LCY a 20 per cent thrust reduction at 400 ft procedure, why? Because the bird was too noisy, and it is well below 100000 Lbs...

This is not a derated take Off, a derated take off, is luring the Engine computers by telling them a virtual temperature, in order to have a lower N1 and lower maintenance costs, flying a derated take off does not withdraw the NADP.

Anyway, for AOC holders, get to Part B, for the others RTFM..:cool:

Empty Cruise

12th Apr 2009, 09:45

CL300,

Agre 100% :D If there is a local procedure, of course you follow it. We know the places where special procedures are required (LCY, TEB etc etc) and stick wih how the OEMs tell us how to fly their product.

Anything outside that and we're into space shuttle teritory :ok: My 1500 ft AAL-remark was obviously not aimed at you or other LCY/TEB/ARN-operators.

Empty

Dumbledor

12th Apr 2009, 12:02

GSPOTs Lost wrote: ''after all its the N1 thats making all the noise not the physical position of the aircraft!'' :confused:

Isn't the whole reasoning behind a steep initial climb as advocated by ICAO to do with getting the noise away from the ground as fast as possible to contain the highest decebels with a small radius of the apt. A 146 flown 100ft over your head at T/O pwr (as heard from the LCY Jet centre ramp) is deafening but from the west end of Victoria dock (by the cracking Thai restaurant!) the noise is much reduced, and probably without a reduction in pwr by then. The noise reduces by inverse square law I believe. If the 146 flew a shallow initial climb it would increase the noise recorded by the monitors below.

I agree with GSPOT about the fact that most bizjets (not converted airliners) get airborne quicker but this allows them to get well above the noise monitors. The engines in theory produce less noise than a bigger engine of similar bypass ratio. (however Falcon 2000s (CFE 738), Beech 400 and Citation V/ultra (both with JT15 -5's) could be quieter!)

It sounds like PL is doing things by the book when derating the BR700's, but it is not something I would chose to do with the same kit unless it was an SOP. This is done for engine life not noise anyway. The MSP contract takes care of the engine wear I thought. Does the MSP company charge less if derated pwr is used? (new ground for me..)

The LJ45 according to the QRH is rotated to betwwen 9 to 14 deg depending on performance, but our SOP is to go for 15deg and T/O pwr to 1000' before setting climb pwr. The 15deg is for terrain clearance, noise, and to reduce the risk of the bird strike. At 1000' power is reduced to Max continuous, or less for an early level off. No consideration is given to reduce below Max continuous for noise purposes. These are no like Viper engines! At a modest 3500 to 4000fpm at 250kt we are reducing the ground noise at a fair rate. . (Not like the ROC of a -31/35 or -60 though :{) We don't try to adher to the ICAO or sid noise profiles, just the level restrictions.

D

G-SPOTs Lost

12th Apr 2009, 14:45

Dumbledor

When I refer to the aicraft position, I probably didn't explain myself properly, a properly perfectly flown NADP flown form a runway intersection will be louder than that from the numbers. Taken to the extreme an aircraft with a double engine failure will not cause the airport any noise complaints.

We are fortunate that we are overpowered, Noise abatement with the exception of LCY/F7X/JT15 et all is not a major factor in our thought process unlike the very heavily monitored airline crews who have to give it great consideration. They do not need to ensure the favourite newspapers are available for their passengers or indeed load the bags - horses for courses

I fully agree and incidentally Im with empty cruise when he refers to KISS, one has to really appreciate the scale of the problem when deciding upon an appropiate response.

Im at MCO right now on a 680 recurrent and have just had my windows rattled last night by a very heavy Virgin 747 which probably was only clearing 800-1200 fpm having used all 3500m of runway! If he brought his TL's back by a couple of inches in much the same way the VAST majority of bizjet crews do he would have been parked next to my car at the hilton

In the vast majority of cases (typical bizjet payloads), in the vast majority of bizjets (notwithstanding the noisy types) at the vast majority of airports there really isnt a problem so if it aint broke and all that....

If you fly a 7X to LCY most days then worry about it, if you fly a CJ2 out of 10000ft r/w's then dont, if you fly a heavy Ultra then worry about it sometimes....KISS

The ICAO documentation will be there to encompass the loudest legacy aircraft at the most stringent airports. Like all aviation legislation they always need to account for the lowest common denominator.

As this is a Bizjet forum can we forget about derated takeoffs - if you are lucky enough to fly a BBJ then you're only now allowed on these forums by the good grace of the lowly slowtation/similar others drivers anyway so stop rubbing it in with your airliner derived bizjets :ok: :ok: :ok: